Articles (the, a, an) are not used in Japanese or Chinese, but are very important in English. Articles add a precision that is very appropriate for scientific writing.

Theis a definite article that refers to a specific thing, person or group that should be known by the reader. It may also indicate a general conception, and is used for anything that is uncountable.

example:

A review of theliterature indicated..."

"Theinformation for each cell..."

The indefinite article ameans one, or may indicate a thing that would not be known by the reader, which has not been mentioned previously.